Wireless-telegraph system.



No. 822,936. PATENTED JUNE 12,1906.

L. DB FOREST. WIRELESS TELEGRAPH SYSTEM.

APPLICATION FILED IBB, 2, 1906.

UNITED STATES PATENT OFFICE.

LEE DE FOREST, OF NEW YORK, N. Y.

WlRELESS-TELEGHAPH SYSTEM.

Specification of Letters Patent.

Patented June 12, 1906.

duplication Filed February 2,1906 Serial No. 2Q9,09l.

is coupled to an ()l'W-fl oscillating or rl'ldinting circuit; and the o)jcct of my invention is to provide a con )lcd wirelcssdcle rsph systemwhose nntural modc of vihrution is 1n011oporiodici As is now wellundcrstood, tho rcsultant vihrnt-ion produced by the natural oscillatoryrestoration to elect rical cquilihrium of a cow plcd system consistin oftwo circuits, both of which when isolntcd hnve the snmc natural pcriod,is not in general monopcriodic, but is multiperiodic, consisting of a,lcnst two frcqucncies, neithcr our of which is cq unl to that natural toeither of said circuits. lhns if the wuvcs radiated by such a systcm hcmeasured by n wave-motor at least two unvo lcngths will hc found, sothat if :1 curve hc plottcd having as its ordinatcs the currents orpotentials dcuclopod in thc wave-motor circuit and as its nhscisszc theprogrcssivclyvarying vnlucs of thc l'rcquoncics natural to said wnvcmctcr circuit, at least W0 nmxima of current or potential willhcohscrvml, and it will he found thnt thc l'rcqucncics corresponding tosaid maximal nrc not tho snow as lhosc natural to oithcr of thccomponent circuits of the couplcd system. in nirclcss tclcgraplrvsuchniuliipcriodic vibration rcndcrsaccumlc tuning impossihlc, for thcrcarc in lcnst two frcqucncics, and thercl'orc a rccciving-circuit can heattuned to either one. of them, and also it rcndcrs transmissioninclliciont, for the radial-ed cncrgy is distrihutcd over or dlvidedhctwocn waves of two lrcquoncics instead of living concentrated intowai'cs of onc frequcncy. 'lhcrclorc 1n ordcr to rcndcr sconrate tuningand cflicicnt transmission possible it is nsccssnrv to employ atransmitting systcm which will dcvclop clcctromagnctio wavcsoi' a singlelrcqucncy and u'rccciving systcm-which will rcspond to \YflYLS of hut usmglc frequency. Various systcnis known as loosolyoonplod syslcms havehccn doviscd for accomplishing tho foregoing results,

but Lhcsc in cncrnl de )cnd upon loose magnctic linkngc hetwccn theantcnna and its alssociutcd transmitting or rccciving circuit, andthcrcfore arc nnsuitcd for commercial loiignlistiuicc working. While theliterature of this lirt abounds in mathematical treatises on the laws ofcoupled systcms, i find that th s lollowingsimple considerations suiliceto explain the phenomena: Referring to thcdingrain shown in Figure],which represents, substantially, the circuit arrangements dcscribed inmy Patent No. 8GZ',850, October 24, 1905, it will he observed that whenlhc sonorous circuit C S L, including the condonser C, spark-gap S, andinductance L, orcstcs oscillations in the antenna system A L E, whichwhen isolated has the some natural period as said sonorous circuit, suchoscillations have two paths from the top of thcantenna in (HLIllL Onepath consists of tho antenna A, the inductance L, and oarth connection DE. The other path consists of the antenna A; the condcnscr (J, thespark-gap S, the conductor l D, and the earth conncotion I E: The twosaid paths are not of Bqjlfll periods,

for the former has a relutivcly lar e period, corresponding to arelatively low re uency as compared to the liittenhecmlse thc iormcrpath includcs the capacity and inductance of the antenna, the lumpedinductance of the coil L, and the capacity and inductance of thc earthconnection, but no lulnpcd caacity, whereas the lattcr path includes nolllmpcd inductance, but only thc distributcd inductance of thc circuit'A B S F D E and the resultant capacity of said circuit. which is ofconrsc much snnillcr than cithcr the disirihutod cspncli of said circuitor thclninpcd capacity of thccondcnscfl. includcd thcrcin, the twocnpncilics hcin; connected in scrics. Inasmuch as the two paths arc notequal in period and us cnch vihrulcs in its UWH nutnrnl,

pcriod, it follows that a complex oi; mull pcriodic wave is radinlcd. I.lhou'm cr, thc lwo paths can hc nnulc equal 1n pcriod, lhunscillstionsin lhcsystcm will have but oncfroqucncy, and thecloctronmgnctir u'avcsrudinlcd ln' said system will be lnonoporiodiia My invent ion consistsin means for making the aforesaid two paths from thc top of the anlcnnuin earth c 118.] in pcriod and will lm cxplaincd with lljeienoc to thodrawings which nccompnnyand form a part of this specification.

In thedrawings, Fig. 1 represents in dia grammatic form a wireless-taleraph transmitting system already referre "to. Fig. 2 representsdiagrammatically a wirelcsstelegraph transmitting system embodying theprinciples of the present invention; and Figs. 3 to 6, inclusive,reqresent modifications of the system shown in ig. 2.

In the figures, L L L are inductances.

C O are condensers. Y

M is a transformer.

G is an alternator.

K is a key.

S is asparlr-ga S S represen a double spark-gap, and A is an antennaearthedat E.

In Fig. 2 the condensers C C may be equal in capacity and the coils L Lmay be equal in inductance. When so constituted, the natural period-ofthe circuit C L L C S is equal to thenatural cried of either of itscomponentparts S C and U0, for by utting said com 'onent parts in seriesthe resu tant capacityo the circuit C LL 0 S is one-half that of eithercondenser C or C, while the resultant inductance of said circuit isdouble that of either coil L or L. The fact that one of the I com onentparts of the oscillatin circuit C L L C S includes thespark-gap S oesnot appreciably affect the equality of the aforesaid natural periodsbecausethe resistance of the gap when sparlrs are passing is only abouttwo 'or three ohms. The electromagnetic constants of the antenna A asand the earth connection 11; E are so chosen that the fundamentalnatural period of the system A w y E,

hereinafter referred to as the antenna system, is e ual to that of theclosed oscillating circuit C L C S, which in turn, as above explained,is equal to the natural Period of each of its component parts a: LG S yand :cL C y. It will now be seen that the two paths from the top of theantenna to the earth E" are eqlual in natural eriod, so that therefore te electrical oscilations developed in the antenna system have but onenatural rate of vibration and that therefore the resultingelectromagnetic waves are mono eriodic in character. Furthermore, it wil be noted that the frequency of said oscillations and said waves isequal to the frequency natural to the circuit C L L C S, which is equalto the fre uencynatural to either of the com' ionents 0 saidcircuit--viz., :c L C S 'y and w L U 'y -and which is equal also to thefrequency natural to either of the two paths from theto of the antennato earthviz.,A w L (I S y and A a: L C y E. The'reason why the said twopaths are equal in period {0 the losed oscillating circuit 18substantial y the same as that above set forth in explaining why the twocomponents ofsaid closed oscillat ng circuit were equal in period to.the

said circuit and is that the systems A w L C S y E and A as L 1 y E eachhave a resultant capacity c ual to one-half that of the condensers Q lor of the antenna system and a resultant inductance equal to twice thatof the coils L L or of the antenna system, provided that the capacity ofthe antenna system is equal to that of the condensers C C and theinductance of the antenna system, is equal to that of the coils L L.

Although for the purpose of more clearly explaining my invention I havedescribed the condensers C C as being equal in capacity and the coils LL as being equal in inductance and although such. )roportionment ispreferred,I donotwish to be limited thereto, or it will be apparent thatmy invention consists in making the two paths from the to of the antennato earth equal in period and t at this may be accomplished in a varietyof ways. For example, the condensers C C may be unequal in capacity andthe coils L LInay be unequal in inductance; but they must be soproportioned that the product C L is equal to the roduct C L and thenthe two paths to cart from the top of the antenna will each have anequivalent efiective inductance and effective ca acity and will be equalin natural period. n this case said natural period will be c ual to thatof the closed oscillating circuit L L C S and will be determined hy theproduct g b, (L L), and this in turn will be seen to be equal to theproducts C L or C L when G L G L. In short, the results obtained bymaking the condensers C C unequal in capacity and the coils L L unequalin inductance, but so proportioned that C LzC L is identical to theresult obtained/when the two condensers are made equal in capacitfl andthe two coils equal in inductance, is not to be understood from theforegoing, however, that it is necessary to inake the capacity'of theantenna system c ual to that of the condensers C C or to make t cinductance of the antenna system c ual to that of thc'coils L L, for, asshown in igs. 5 and 6, the inductance of the antenna s stem may begreater than that of the coils or L, while the capacity of thecondensers C or C in such case must necessarily be correspondinglygreater than the ca acity of the antenna s 'stem.

he s stem shown in ig. 3 is electrically the equlvalent of that shown inFig. 2, the particular circuital arrangement of the condensers and coilsbeing immaterial.

In the system shown in Fi 4 each of the component parts of the closeoscillating circuit includes a s ark-gap S S, respectively, thespark-ball 1 eing in one part and the ball 3 in the other, wlnl thecenter ball 2 is earthed at E. In this case the two paths to earth fromthe top of the antenna are absolutely identical in every respect.

irncted and arranged that the two )aths innn the top of the antenna tocart are equal in natural period, and means associated with saidoscillating circuit for causing the same to execute electricaloscillations.

7. In a system for developing and radiatlug inonoperiodicelectrmnagnetic waves, an antenna, a circuit including a capacity, aninductance and a s ark-ball connected theretoat a point, anot 1ercircuit includin a capacity, an inductance and a spark-hail connected tothe antenna system at the same point, the capacities and inductances ofsaid circuits being-s0 proportioned that the said circuits are eq'ualinnatural period, a third spark-ball located between said spark-balls andan earthed conductor connected to said spark-ball.

8.. In a wireless-telegraph transmitting system, an antenna system, aclosed oscil1at ing circuit connected thereto and so constructed andarranged that the two paths from the topoi the antenna to earth are identical, and means associated with said oscillating circuit for causingthe same to execute electrical oscillations.

9. In a wirelesstelegraph transmitting system, an antenna system, aclosed oscillat ing circuit connected thereto and so constructed andarranged that the two paths from the top of the antenna to earth haveequivalent effective capacity and effective inductance, and meansassociated with said oscillating circuit'for causing the same toexecut'e electrical oscillations.

In testimony whereof I have hereunto subscribed my name this 26th day ofJanuary,

LEE DE FOREST. W'itnesses J. H. HARRIs, R0151. S. MILLr/r'r.

